ENGN8637. Advanced Topics in Communications. Your Title

Transcription

1 ENGN8637 Advanced Topics in Communications Your Title Your name Research School of Engineering, ANU submitted on 18/March/2018 Contents 1 Introduction 1 2 A New Section 3 3 Yet another Section 4 4 Conclusion 4 1 Introduction Let us introduce some latex. Here are some itemisations 1. Transmitter, which consists of: Interleaver: it transforms a bit sequence into a bit matrix; 1

2 Modulator: it transforms a set of bits into a complex symbol which it then rotates and Q-delays; 2. Channel simulator: it corrupts the complex symbols by changing their phase/amplitude and adding noise; 3. Receiver, which consists of: Demodulator: it reverses the Q-delay and then demaps the complex symbols back to bits either by using maximum likelihood or soft-demapping; De-interleaver: it transforms the bit matrix back to bit sequence. Or simply Interleaver: it transforms a bit sequence into a bit matrix; Modulator: it transforms a set of bits into a complex symbol which it then rotates and Q-delays; 2

3 2 A New Section Fig. 1 shows the overall block diagram. Figure 1: Overall block diagram of DVB-T2 showing the BICM sub-modules to be implemented in the project. Some equation examples T DM (N) = NM M 2 (1 + Q) + N (1) where T DM is the distributed MIMO aggregate throughput and Q is a letter of the alphabet. ρ(r) = N πr 2 o exp ( r2 r 2 o ) (2) L = N πr 2 o Ro 0 2πrdr exp ( r2 r 2 o ) (3) 3

4 3 Yet another Section Here is a table Table 1: Comparitive performance of the cellular and the distributed wireless networks Cellular Distributed N Bases M LM User BW B B Total Occupied BW LB B Total Base P rad > LMP o LMP o P rad per Base > LP o P o Uplink BW per remote B B Range (99%) 2.15r o Lro and here Yet another table... 4 Conclusion The conclusion... References [1] DVB Document A122, Frame Structure, channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2), June [2] M. Yu, A study of DVB-T2 standard with physical layer transceiver design and implementation, MPhil Thesis, Australian National University,

5 Notation Description c N ldpc R c L pr c p c b C X X θ X d H W Y V v b v the binary LDPC codeword to be interleaved the length of c the code rate of c the a priori log-likelihood ratio (LLR) information of c the codeword after parity interleaving the codeword after bit interleaving the bit matrix after de-multiplexing a rotated constellation symbol, which is a complex number the set of symbols generated from C the rotation angle (anti-clockwise) the set of Q-delayed symbols from X a fading channel coefficient, which is a complex number an AWGN noise instance, which is a complex number the received symbol of X d after channel the bit matrix after de-mapping the codeword after multiplexing the demapped LDPC codeword Group ID N ldpc R c Modulation Group ID N ldpc R c Modulation A QAM E QAM B QAM F QAM C QAM G QAM D QAM H QAM I QAM J QAM K QAM 5

6 APPENDIX A: LINUX When you connect to the LINUX O.S. using PUTTY (secure shell), you are presented with a terminal interface. This is an old-fashioned but very effective way to interact with a computer. In this section we describe the structure of LINUX file system and how you can use LINUX. First off type ls /. You should see the following. debian@beaglebone:~$ ls / bin dev home lost+found mnt proc run selinux sys usr boot etc lib media opt root sbin srv tmp var / refers to the root file system. This is the top folder or directory. There are a number of subfolders as follows: bin Contains many of the binary files that constitute the commands in the O.S. boot Contains kernel images and configutation files. The kernel refers to the LINUX operating system itself. dev Contains system interfaces (files) to the LINUX character and block devices (but not the network devices). Take a look at them by typing ls /dev. These devices can be opened as files by programs and allow the program to access LINUX device drivers. Can you think of what any of the devices refer to? etc Is where most of the system configuration scripts are located. home Is the home folder where the files are located of users who can access the system. There is only one user on my BBB system with uid debian. When you log in you arrive directly at your home folder. Here this is /home/debian. lib These are where the binary libraries are located. On WINDOWS think dlls. media This is where external storage devices can be mounted. Such devices include CD-ROMS, flash and external hard drives. Note tha term mount. The mount command is used to connect a folder (usually but not necessarily located in /media) to a block device in /dev. This allows the block device to be accessed as a folder. This may seem strange for MAC and WINDOWS users where mounting is performed transparently by the O.S. mnt serves a similar purpose to media proc Is actually a file system that is not located on the hard drive - or any block device. proc is located in RAM and is a volatile folder containing all of the system information. For example try cat /proc/cpuinfo to see what is contained in this file. 6

7 sbin is the superuser binary director. This is where the administrator-only commands are stored. usr is the usual place where new commands and other system files get stored when a user installs new software on LINUX. The following is a short list of basic unix commands that can be executed in the xterm. These commands are big programs usually with many options and can be very powerful. If you wish to learn more about a command type, man COMMAND NAME >. The man refers to the manual or man page for the command. man produces a scrollable interface inside the xterm. To navigate, simply use the arrow keys. To quit type < quit >. ls l list the files in the current directory in detailed format. cat FILE NAME.txt dumps the contents of a text file to the terminal. grep STRING FILE NAME.txt. List all occurrences of STRING in file FILE NAME. Note that wildcards are possible: grep STRING.txt. cp FILE NAME TARGET. Copy file FILE NAME to TARGET where TARGET could be another file or a directory. In this case the file FILE NAME is left in tact. mv FILE NAME TARGET. Move the file FILE NAME to TARGET where TARGET could be another file or a directory. In this case the file FILE NAME is removed. rm FILE NAME. Delete the file FILE NAME. Be careful of this command. The rm command does not transport files to a safe haven such as the trash can. Instead it wipes them completely from the disk. mkdir DIR NAME. Create a directory DIR NAME. rmdir DIR NAME. Delete the directory DIR NAME. Only works if DIR NAME is empty. cd DIR NAME change to folder DIR NAME. format. The command cd takes you to your home folder. df. List total disk usage. Superfast way of finding out how much of your hard drive space is left. mount is used to mount file systems e.g. mount /dev/sdb1 /media/disk ssh allows you to make a connection to another LINUX computer. Example 1: connect to user debian on a machine at IP address : ssh debian@ Example 2: Do the same but also allow an x-session: ssh X debian@ Example 3: Copy a file FILE NAME located in folder DIR1 NAME on the local machine to folder DIR2 NAME on debian@

8 scp DIR1 NAME/FILE NAME : /DIR2 NAME/FILE NAME note that DIR2 NAME has to be an absolute path. DIR1 NAME can be an absolute path but may be a relative path e.g../ is the current folder. nano is a simple screen text-editor with a built-in description of its ten only commands. The figure below shows how to use nano to create a simple c-program that prints Hello World! to the terminal. gcc o myfile myfile.c: compile C-program myfile.c into executable myfile. To run myfile, cd to the folder where it is located and type./myfile. If you are running X-windows the following are useful commands. /usr/bin/sof f icew orddoc.docx to open a WORD document /usr/bin/evincep DF F ile.pdf open a PDF /sbin/if conf ig: display the status of network devices. An example is shown below. Note that there are three network interfaces: eth0 the main ethernet interface, lo the loopback interface and usb0 the USB network interface (providing ethernet connectivity). debian@beaglebone:~$ /sbin/ifconfig eth0 Link encap:ethernet HWaddr 90:59:af:5b:cd:c3 inet addr: Bcast: Mask: UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:40 lo Link encap:local Loopback inet addr: Mask: inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:68 errors:0 dropped:0 overruns:0 frame:0 TX packets:68 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:6434 (6.2 KiB) TX bytes:6434 (6.2 KiB) usb0 Link encap:ethernet HWaddr c6:fe:62:d7:9a:82 inet addr: Bcast: Mask: inet6 addr: fe80::c4fe:62ff:fed7:9a82/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 8

9 RX packets:630 errors:0 dropped:0 overruns:0 frame:0 TX packets:448 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:51153 (49.9 KiB) TX bytes:96967 (94.6 KiB) Finally there is /usr/bin/sudo. This command can be used to execute superuser commands by a regular user - provider the uid is stored in /etc/sudoers. You even need /usr/bin/sudo just to look at the file /etc/sudoers. A useful command requiring /usr/bin/sudo is /usr/bin/sudo halt which shuts down LINUX. Notice that these comands have been invoked from the folders where they are located. It is unnecessary to do this if these folders are in the PATH. PATH is an environment variable that can be found using the command echo $PATH. UDP code /* ** talker.c -- a datagram "client" demo */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define SERVERPORT "9999" // the port users will be connecting to int main(int argc, char *argv[]) int sockfd; struct addrinfo hints, *servinfo, *p; int rv; int numbytes; 9

10 Figure 2: Screenshot of nano in action 10

11 if (argc!= 3) fprintf(stderr,"usage: talker hostname message\n"); exit(1); memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_DGRAM; if ((rv = getaddrinfo(argv[1], SERVERPORT, &hints, &servinfo))!= 0) fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; // loop through all the results and make a socket for(p = servinfo; p!= NULL; p = p->ai_next) if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) perror("talker: socket"); continue; break; if (p == NULL) fprintf(stderr, "talker: failed to bind socket\n"); return 2; if ((numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0, p->ai_addr, p->ai_addrlen)) == -1) perror("talker: sendto"); exit(1); 11

12 freeaddrinfo(servinfo); printf("talker: sent %d bytes to %s\n", numbytes, argv[1]); close(sockfd); return 0; /* ** listener.c -- a datagram sockets "server" demo */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define MYPORT "9999" // the port users will be connecting to #define MAXBUFLEN 100 // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) if (sa->sa_family == AF_INET) return &(((struct sockaddr_in*)sa)->sin_addr); return &(((struct sockaddr_in6*)sa)->sin6_addr); 12

13 int main(void) int sockfd; struct addrinfo hints, *servinfo, *p; int rv; int numbytes; struct sockaddr_storage their_addr; char buf[maxbuflen]; socklen_t addr_len; char s[inet6_addrstrlen]; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4 hints.ai_socktype = SOCK_DGRAM; hints.ai_flags = AI_PASSIVE; // use my IP if ((rv = getaddrinfo(null, MYPORT, &hints, &servinfo))!= 0) fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; // loop through all the results and bind to the first we can for(p = servinfo; p!= NULL; p = p->ai_next) if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) perror("listener: socket"); continue; if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) close(sockfd); perror("listener: bind"); continue; 13

14 break; if (p == NULL) fprintf(stderr, "listener: failed to bind socket\n"); return 2; freeaddrinfo(servinfo); printf("listener: waiting to recvfrom...\n"); addr_len = sizeof their_addr; if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1, 0, (struct sockaddr *)&their_addr, &addr_len)) == -1) perror("recvfrom"); exit(1); printf("listener: got packet from %s\n", inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), s, sizeof s)); printf("listener: packet is %d bytes long\n", numbytes); buf[numbytes] = \0 ; printf("listener: packet contains \"%s\"\n", buf); close(sockfd); return 0; /* ** rtl_decode.c -- decodes rtl-sdr binary IQ to HEX */ 14

15 #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> main(int argc, char **argv) char infilename[200]; char outfilename[200]; char *name; FILE *infile; FILE *outfile; unsigned char Ichar, Qchar; int flag; int sample_counts; int Nbytes; printf("usage:./rtl_decode infile outfile Nbytes\n"); printf("default filename=file.in Nbytes = 200\n"); if( argc < 4 ) strcpy(infilename,"file.in"); strcpy(outfilename,"file.out"); Nbytes = 200; else strcpy(infilename,argv[1]); printf("infile = %s\n",infilename); strcpy(outfilename,argv[2]); printf("outfile = %s\n",outfilename); Nbytes=(int)atoi(argv[3]); printf("%d\n",nbytes); 15

16 infile = fopen(infilename,"r"); if( infile == NULL) printf("could not open file\n"); exit(exit_failure); outfile = fopen(outfilename,"w"); if( outfile == NULL) printf("could not open file\n"); exit(exit_failure); flag = fscanf( infile, "%c", &Ichar); flag = fscanf( infile, "%c", &Qchar); // while( EOF!= flag ) for(sample_counts=0;sample_counts<nbytes;sample_counts++) fprintf(outfile, "%d,%d\n", (int)ichar-128,(int)qchar-128); flag = fscanf( infile, "%c", &Ichar); flag = fscanf( infile, "%c", &Qchar); fclose(infile); fclose(outfile); 16